1. Field of the invention
The present invention concerns the guidance of supersonic missiles (submunitions) especially in the coast or deceleration phase. It is particularly, but not exclusively, directed to guided missiles propelled at high speeds (at least Mach 2 and in practise Mach 4 to 5) of the so-called high velocity missiles type operated at low altitude and designed to neutralize late detected airborne or terrestrial attackers such as, for example, tanks, combat helicopters or aircraft flying at high speed at low altitude and capable of sudden evasive maneuvers.
The invention is therefore directed in particular to a missile whose mission comprises a first boost or acceleration phase, during which the position of the center of gravity of the missile varies considerably in the longitudinal direction due to the consumption of propellants, followed by a second, coast or deceleration phase in which the position of the center of gravity remains fixed.
The invention is also directed to a ballistic missile (submunition or projectile) previously accelerated to the required speed by booster propulsion means which then separate. One finds again the aforementioned phase in which the position of the center of gravity is fixed.
The maneuvrability required of such missiles or projectiles is such that a low static margin is required, imposing an aerodynamic center which is relatively independent of the Mach number.
There are currently four control concepts:
1--aerodynamic control using tail fins. Said fins must have a very limited span to avoid any risk of flutter in the range of Mach numbers used (around Mach 6). In this case, long wings are necessary to obtain correct stability whatever the Mach number. This formula raises relatively serious problems due in particular to the actuators to be accommodated around the nozzle and the long wings to be carried by the propulsion unit;
2--aerodynamic control using nose-mounted foreplanes or "canard" fins. However, in this case conventional control methods are subject to known problems, namely the non-linearity of the aerodynamic characteristics as a function of the angle of incidence, loss of efficacy in angle of incidence and with high deflection, high hinge moments and virtual impossibility of control in roll;
3--the Thrust Vector Control System (TVCS), which is feasible during the booster phase, but another control formula is then needed (deceleration phase because there is no other propellant stage operating during the remainder of the mission;
4--finally, there is the concept using side jets: when they are nose-mounted they cause an area of increased pressure on the upstream side of the jets and an area of reduced pressure on the downstream side extending as far as the aft planes. Said jets create a favorable interaction aerodynamic moment which is added to the propulsive moment. However, this method of control provides inadequate maneuverability as it requires the mounting of a bulky and prohibitively heavy pneumatic or gas generator system in the nose of the missile.
An object of the invention is to alleviate the aforementioned disadvantages, especially in the guided deceleration phase, using the combination of one or more retractable spoilers and fixed planes (including any foreplanes), which results in a significant dynamic pressure effect due to the deployment of the spoiler. This advantageously makes the missile extremely maneuvrable at the cost of a minimal increase in weight.
In the context of the invention, the term "missile" is to be interpreted in a broad sense encompassing the concepts of missiles proper, submunitions and projectiles.